pgr_dijkstraCost
Using Dijkstra algorithm implemented by Boost.Graph, and extract only the aggregate cost of the shortest path(s) found, for the combination of vertices given.
Availability
The pgr_dijkstraCost
algorithm, is a good choice to calculate the sum of the costs
of the shortest path for a subset of pairs of nodes of the graph.
We make use of the Boost’s implementation of dijkstra which runs in
\(O(V \log V + E)\) time.
Summary
pgr_dijkstraCost(edges_sql, from_vid, to_vid [, directed])
pgr_dijkstraCost(edges_sql, from_vid, to_vids [, directed])
pgr_dijkstraCost(edges_sql, from_vids, to_vid [, directed])
pgr_dijkstraCost(edges_sql, from_vids, to_vids [, directed])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Using defaults
pgr_dijkstraCost(edges_sql, from_vid, to_vid)
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example:  From vertex \(2\) to vertex \(3\) on a directed graph 

SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
2, 3);
start_vid  end_vid  agg_cost
++
2  3  5
(1 row)
pgr_dijkstraCost(edges_sql, from_vid, to_vid [, directed])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example:  From vertex \(2\) to vertex \(3\) on an undirected graph 

SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
2, 3, false);
start_vid  end_vid  agg_cost
++
2  3  1
(1 row)
pgr_dijkstraCost(edges_sql, from_vid, to_vids [, directed])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example:  From vertex \(2\) to vertices \(\{3, 11\}\) on a directed graph 

SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
2, ARRAY[3, 11]);
start_vid  end_vid  agg_cost
++
2  3  5
2  11  3
(2 rows)
pgr_dijkstraCost(edges_sql, from_vids, to_vid [, directed])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example:  From vertices \(\{2, 7\}\) to vertex \(3\) on a directed graph 

SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
ARRAY[2, 7], 3);
start_vid  end_vid  agg_cost
++
2  3  5
7  3  6
(2 rows)
pgr_dijkstraCost(edges_sql, from_vids, to_vids [, directed])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example:  From vertices \(\{2, 7\}\) to vertices \(\{3, 11\}\) on a directed graph 

SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
ARRAY[2, 7], ARRAY[3, 11]);
start_vid  end_vid  agg_cost
++
2  3  5
2  11  3
7  3  6
7  11  4
(4 rows)
Parameter  Type  Default  Description 

edges_sql  TEXT 
Inner SQL query as described below.  
start_vid  BIGINT 
Identifier of the starting vertex of the path.  
start_vids  ARRAY[BIGINT] 
Array of identifiers of starting vertices.  
end_vid  BIGINT 
Identifier of the ending vertex of the path.  
end_vids  ARRAY[BIGINT] 
Array of identifiers of ending vertices.  
directed  BOOLEAN 
true 

Column  Type  Default  Description 

id  ANYINTEGER 
Identifier of the edge.  
source  ANYINTEGER 
Identifier of the first end point vertex of the edge.  
target  ANYINTEGER 
Identifier of the second end point vertex of the edge.  
cost  ANYNUMERICAL 
Weight of the edge (source, target)


reverse_cost  ANYNUMERICAL 
1  Weight of the edge (target, source),

Where:
ANYINTEGER:  SMALLINT, INTEGER, BIGINT 

ANYNUMERICAL:  SMALLINT, INTEGER, BIGINT, REAL, FLOAT 
Returns SET OF (start_vid, end_vid, agg_cost)
Column  Type  Description 

start_vid  BIGINT 
Identifier of the starting vertex. Used when multiple starting vetrices are in the query. 
end_vid  BIGINT 
Identifier of the ending vertex. Used when multiple ending vertices are in the query. 
agg_cost  FLOAT 
Aggregate cost from start_vid to end_vid . 
Example 1:  Demonstration of repeated values are ignored, and result is sorted. 

SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
ARRAY[5, 3, 4, 3, 3, 4], ARRAY[3, 5, 3, 4]);
start_vid  end_vid  agg_cost
++
3  4  3
3  5  2
4  3  1
4  5  3
5  3  4
5  4  3
(6 rows)
Example 2:  Making start_vids the same as end_vids 

SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
ARRAY[5, 3, 4], ARRAY[5, 3, 4]);
start_vid  end_vid  agg_cost
++
3  4  3
3  5  2
4  3  1
4  5  3
5  3  4
5  4  3
(6 rows)
Indices and tables